The Fuel of Emerging Life
PROTOMETABOLISM could not have unfolded without a supply of energy, together with the means for productively exploiting this energy. The life-building complexification process was uphill all the way. To make it downhill and, therefore, able to occur spontaneously, a sufficient supply of energy was essential. There were plenty of energy sources on the prebiotic Earth, in the form of sunlight, ultra- violet radiation, electric discharges, shock waves, heat, and chemical upheavals of various sorts. Which among these various sources of energy did emerging life exploit? And, especially, how was the raw power in the prebiotic setting converted into productive life-creating events?
If, in accordance with the congruence rule, we ask present-day life for a hint with regard to these questions, we immediately run into a problem. The most important energy generators of living organisms today depend on the operation of highly complex substances organized within the fabric of an intricate, filmlike structure, or membrane. Could such arrangements have arisen early enough to satisfy the energy requirements of emerging life?
Several authors believe so. In a book devoted to bioenergetics, Franklin Harold, a biochemist from the University of Colorado, does not hesitate to head an important section with the declaration: "In the beginning was the membrane."1Clair Folsome, from the University of Hawaii, has proposed that primitive membranous vesicles might have formed from some oily "scum"--what I have called "goo" in chapter 1--which must have been abundant in the prebiotic world, and that these vesicles might have developed into photochemical "protobionts" by association with some light-catching molecule.2 This and other similar proposals cannot be dis-